Prognostic role of lymph-node level involvement in patients undergoing axillary dissection for breast cancer

Aims. Clinical records of patients undergoing surgery for breast cancer were reviewed in order to evaluate the prognostic role of lymph-node level involvement. Methods. From 1982 to 1991, 1143 patients had radical mastectomy or conservative surgery with total axillary dissection: 461 patients of mean age 57.1 years (range: 25-89 years) were lymph-node positive (pN1); 369 patients (80%) had radical mastectomy; and 92 patients (20%) had conservative treatment plus post-operative radiotherapy, with the same mean number (n = 16) of lymph nodes collected in the surgical specimen. Data were analysed for the number of positive lymph nodes and level of involvement. Results. Level I, Levels I+II and Levels I+II+III were involved in 44.9, 18 and 21.4% of patients, respectively; 'skip metastases' occurred in 72 of 461 pN1 patients (15.5%). A univariate analysis showed that prognosis was directly related to the number of levels involved (P<0.001), and skip metastases had the same prognostic role as Level I involvement. The numbers of involved lymph-node levels and metastatic lymph nodes were well correlated; multivariate analysis showed that involvement of Levels I and III was independently correlated with prognosis. After adjustment for age and number of positive lymph nodes, the number of involved lymph-node levels was an independent prognostic factor, with highest predictability when all three lymph-node levels were positive (P=0.009). Conclusions. The prognostic value of lymph-node status should be defined not only by the number of metastatic lymph nodes, but also by the number of levels of involvement.